Continuous molding of fastener products and the like and products produced thereby

ABSTRACT

Improvements are disclosed for an apparatus for continuously molding small fastener elements integral with a base web from a flowable resin. The apparatus comprises a cylindrical mold roll rotatable about an axis and defining small fastener element-shaped mold cavities in the surface thereof, and pressure-applying means to apply operating pressure to force the resin into the cavities at a pressure zone. The pressure-applying means and mold roll define a mold gap therebetween for forming the base web. The advantageous use of relatively long mold rolls, to produce a correspondingly wide web, and the use of higher molding pressures, e.g. to form very small fastener elements, is enabled by various improvements, including means to maintain the mold gap at a desired thickness profile across the length of the molding region of the mold roll under operating pressure. In some cases the pressure-applying means includes a pressure roll, in other cases it includes a resin nozzle assembly or pressure head. In some other cases it includes a belt. Various control schemes are also disclosed, as are means to provide cooling. In some particularly useful embodiments, at least one of the rolls of the apparatus has a resiliently deformable surface. Methods of molding fastener elements directly on a sheet material, such as sandpaper, are also disclosed, as well as methods for laminating.

BACKGROUND OF THE INVENTION

[0001] This invention relates to improved equipment and methods formaking continuous fastener products and the like, and to productsproduced by the equipment and methods.

[0002] Fastener products, such as hook components of hook-and-loopfasteners, are manufactured by a continuous molding method employing acylindrical mold roll which has fastener-shaped cavities formed in itsperiphery. Often the mold roll is formed of an axially compressed stackof ring-form mold plates. In operation, molten polymer from an extruderis is introduced into a pressure zone in which the molten polymer isforced under high pressure into the fastener cavities of the cooled moldroll, to form fastener elements (e.g. hooks) integrally molded with abase layer. In some cases the pressure zone is a nip formed by a moldroll and an adjacent pressure roll. In other configurations the pressurezone is formed between a conforming stationary pressure head and a moldroll. Typically, the smaller the fastener elements (or the like), thefaster the optimal production speed. The more viscous the resin, or thelower the temperature of the cooled roll, the higher must be thepressure achieved in the pressure zone in order to make a satisfactoryproduct. Typically, mold rolls of about 10 inch diameter and 12 inchesin axial length have been employed.

SUMMARY OF THE INVENTION

[0003] We have realized that many advantages can be obtained byemploying longer mold rolls and correspondingly wide pressure zones toform wide products, while providing means to accommodate effects of thedistribution of pressure along the length of the mold roll. By thismeans, products molded with wide widths can have uniform productthickness and other properties previously found only in narrowermaterials.

[0004] We also have realized that many advantages can be obtained byraising the pressure in the pressure zone, with a conventional roll or alonger roll, to form products having finer features while providingmeans to accommodate effects of the distribution of pressure along thelength of the mold roll.

[0005] We have realized that, because of the construction of the moldingregion of the mold roll as a stacked series of rings or plates about acentral shaft, the mold roll has limited bending resistance. As aresult, if the molding region of the mold roll is made long to produce awide product, or if the pressure of the resin is increased, the tendencyof the mold roll to bend away from the pressure zone under the extrememolding pressure can cause small separations between adjacent moldplates and undesirable base layer thickness variation across the widthof the product (i.e. gap variation along the length of the moldingregion). Also, we realize that non-uniform geometry of the pressure zonecan produce detrimental nonuniformity in the pressure distributionacross the pressure zone, which can lead to incomplete filling of someof the mold cavities.

[0006] According to one aspect of the invention, improvements are madein an apparatus for continuously molding fastener elements integral witha base web from a flowable resin. The apparatus comprises a cylindricalmold roll rotatable about an axis and defining small fastenerelement-shaped mold cavities in the surface thereof, andpressure-applying means to apply elevated operating pressure to forcethe resin into the cavities at a pressure zone. The pressure-applyingmeans and mold roll define a mold gap therebetween for forming the baseweb. The provided improvements include means to maintain the mold gap ata desired thickness profile across the length of the molding regionunder operating pressure that would otherwise tend to produce gapvariations.

[0007] The provided improvements are particularly useful if the moldingregion of the mold roll is lengthened to about 12 inches or more or ifthe operating pressure is raised to higher levels, such that the moldroll is subject to loads in the range of about 1000 to 1600 pounds perlineal inch along the mold roll.

[0008] In a preferred configuration, the mold roll comprises an axiallyarranged stack of a large multiplicity of disks, at least many of whichhave mold cavities at their peripheral surfaces.

[0009] In certain advantageous embodiments, the means to maintain themold gap comprises a moving support member on the side of the mold rollgenerally opposite the pressure-applying means. The support member isdisposed to engage the peripheral surface of the mold roll withsufficient force to resist radial deflection of the mold roll.Preferably a support member controller is provided to vary the amount ofengagement between the mold roll and the support member in response tooperating conditions.

[0010] In certain embodiments, the apparatus includes a sensor toprovide operating condition information to a support member controller.In some cases the sensor is constructed to detect the presence of moldedresin on the peripheral surface of the mold roll and the controller isconstructed to disengage the support member from the peripheral surfaceof the mold roll when resin is not present. In certain arrangements, thesensor is constructed to respond to a condition of the apparatus that isrelated to the pressure in the pressure zone.

[0011] In some preferred embodiments of the invention the depth of themold cavities from the surface is between about 0.004 and 0.035 inches,preferably between about 0.005 and 0.020 inches, and more preferablybetween about 0.006 and 0.012 inches.

[0012] Broadly, the invention relates to completed fastener elements andto components or preforms that form a part of, or are modified to form,a completed fastener. The term “fastener element” as used herein isintended to include all of these forms.

[0013] In some embodiments, however, the mold cavities preferably definethe shape of functional fastener elements. In some preferredarrangements the mold cavities at least partially define the shape ofloop or fiber-engaging hook elements, each element having a pedestal orstem portion and at least one head portion that projects to a side ofthe pedestal or stem portion. In other arrangements, the fastenerelements are of mushroom shape or of stem-shaped preforms that aresubsequently processed to form mushrooms or other elements having flator rounded heads.

[0014] In some particularly useful embodiments, the support member thatengages the mold roll has a peripheral surface that is resilientlydeformable to conform, in the vicinity of its engagement with the moldroll, generally to the peripheral surface of the mold roll. In some ofthese instances, the portion of the support member that directlycontacts the surface of the mold roll is of a resilient substance,preferably an elastomeric material.

[0015] In some preferred embodiments the support member comprises agenerally cylindrical roll arranged to rotate about an axis of rotation,while in some other embodiments the support member comprises a beltsupported to engage the mold roll with substantial pressure.

[0016] In some embodiments the means to maintain the mold gap comprisesadjustable structure to elastically deform the shape of thepressure-applying means, to conform to axial deflection of the moldroll. In some cases, the pressure-applying means comprises a pressureroll, the mold gap comprises a nip between the mold roll and pressureroll, and the means to elastically deform the shape is constructed tobend the axis of the pressure roll to maintain the mold gap. In someother cases, the pressure-applying means comprises a nozzle assembly forintroducing the resin to the pressure zone under pressure, the mold gapcomprises a gap between this nozzle assembly and the mold roll, and themeans to elastically deform the shape is constructed to bend the nozzleassembly along the length of the mold gap to maintain the mold gap.

[0017] In some preferred embodiments the pressure-applying meanscomprises a pressure roll rotatable about an axis and positioned to forma nip with the mold roll to provide the mold gap. The means to maintainthe mold gap includes a controller to vary the angle between the axes ofthe pressure and mold rolls to introduce skew to compensate for moldroll deflection under operating pressure.

[0018] In various arrangements according to the invention, means areprovided to extract heat from the surface of the support member to coolthe support member, thus to withdraw heat from the molding process.

[0019] According to another aspect of the invention, an apparatus isprovided for continuously molding two streams of fastener product fromflowable resin, each product comprising a base web with integralfastener elements. The apparatus has a cylindrical mold roll rotatableabout an axis and defining small fastener element-shaped mold cavitiesin its surface in a molding region. The apparatus also has first andsecond pressure-applying means to apply operating pressure to force theresin into the cavities of the mold roll at corresponding first andsecond pressure zones. The first and second pressure-applying means andthe mold roll define corresponding first and second mold gapstherebetween for forming the base webs in the molding region. First andsecond product-removing means are included to remove the product fromthe mold roll. The first and second pressure-applying means areadvantageously arranged on generally opposite sides of the mold roll,such that bending loads applied to the mold roll by the elevatedoperating pressures of the two pressure applying means are substantiallybalanced. Preferably, the mold roll is of extended length of about 12inches or more to produce correspondingly wide webs.

[0020] In some embodiments the first and second pressure-applying meanseach comprises a pressure roll and the first and second mold gaps eachcomprises a nip between the mold roll and a corresponding pressure roll.

[0021] In some other embodiments, the first and second pressure-applyingmeans each comprises a nozzle and shoe assembly for introducing theresin to the corresponding pressure zone under pressure and the firstand second mold gaps each comprises a gap between a corresponding nozzleassembly and the mold roll.

[0022] According to another aspect of the invention, an apparatus, forcontinuously molding small fastener elements integral with a base webfrom a flowable resin, has a cylindrical mold roll rotatable about anaxis and defining fastener element-shaped mold cavities at its surfacein a molding region, and pressure-applying means are arranged to applyoperating pressure to force the resin into the cavities at a pressurezone. The pressure-applying means and mold roll define a mold gaptherebetween for forming the base web in the molding region. Theapparatus includes a roll arranged to engage the mold roll withsubstantial force, and which has a resiliently deformable surface toconform, in the vicinity of its engagement with the mold roll, generallyto the peripheral surface of the mold roll along the molding region.

[0023] In some embodiments, the molding region of the mold roll is ofabout 12 inches or more in length and the resiliently deformable rollcomprises a pressure roll positioned to form a wide nip with the moldroll to provide the mold gap, to form a correspondingly wide web. Inthese and other embodiments, preferably a substantially elevatedpressure is maintained in the pressure zone to produce a load of betweenabout 1000 and 1600 pounds per lineal inch against the mold roll in themolding region.

[0024] In some embodiments, the resiliently deformable roll comprises asupport roll disposed to engage the mold roll on the side generallyopposite the pressure-applying means to resist deflection of the moldroll.

[0025] In some embodiments useful for producing a laminated fastenerproduct comprising a molded web and a backing material, the resilientroll and the mold roll define therebetween a laminating zone forlaminating the molded web to the backing material.

[0026] According to another aspect of the invention, an apparatus forcontinuously molding fastener elements integral with a base web from aflowable resin has a cylindrical mold roll rotatable about an axis anddefining fastener element-shaped mold cavities at a surface thereof,pressure-applying means to apply operating pressure to force the resininto the cavities at a pressure zone (the pressure-applying means andmold roll defining a mold gap therebetween for forming the base web),and a belt arranged to engage the mold roll.

[0027] In some embodiments the belt is arranged to engage the mold rollon the side generally opposite the pressure-applying means to resistradial deflection of the mold roll.

[0028] In some embodiments the belt and the mold roll define alaminating zone therebetween for laminating the molded web to a backingmaterial.

[0029] In some cases, the belt is constructed to extract heat from thesurface with which it is engaged.

[0030] According to another aspect of the invention, certain otherimprovements are provided in an apparatus for continuously moldingfastener elements integral with a base web. The apparatus has acylindrical mold roll rotatable about an axis and defining fastenerelement-shaped mold cavities in the peripheral surface thereof, and anozzle assembly to introduce a flowable resin to the cavities. Thenozzle assembly is constructed and arranged to apply operating pressureto force the resin into the cavities at a pressure zone, and the nozzleassembly and mold roll define a mold gap therebetween for forming thebase web, the apparatus including means to maintain the mold gap at adesired thickness profile across the width of the wide web under theoperating pressure if the roll is lengthened or if the operatingpressure is raised to higher levels such that the mold roll is subjectto loads in the range of about 1000 to 1600 pounds per lineal inch alongthe mold roll.

[0031] In some embodiments the means to maintain the mold gap comprisesa support member disposed to engage the mold roll on the side generallyopposite the nozzle assembly with sufficient force to resist radialdeflection of the mold roll, and a controller constructed to vary theamount of engagement between the support member and the mold roll. Insome cases the support member is resiliently deformable.

[0032] In some embodiments the means to maintain the mold gap comprisesan actuator to elastically bend the nozzle assembly to conform to radialdeflections of the mold roll to maintain the mold gap, and a controllerconstructed to control the actuator to vary the amount of bending of thenozzle assembly.

[0033] According to another aspect of the invention, an apparatus forcontinuously molding fastener elements integral with a base web includesa cylindrical mold roll, preferably of extended length to provide acorrespondingly wide web, and a cylindrical pressure roll. The mold rollis rotatable about an axis and comprises multiple stacked disks havingfastener element-shaped mold cavities in their peripheral surfaces. Thecylindrical pressure roll is arranged to engage the mold roll at a nipto form a mold gap for forming the base web. The pressure roll isconstructed to apply operating pressure to force the resin into thecavities. The apparatus also includes an extrusion die to introduce aflowable resin to the nip, and means to maintain the mold gap at adesired thickness profile across the width of the wide web under theoperating pressure, preferably a substantially elevated pressure.

[0034] In some embodiments the means to maintain the mold gap comprisesa support roll arranged to engage the mold roll on the side generallyopposite the nozzle assembly with sufficient force to resist radialdeflection of the mold roll, and a controller constructed to control theamount of engagement between the support roll and the mold roll inresponse to operating conditions.

[0035] In some embodiments the means to maintain the mold gap includes acontroller to vary the angle between the axes of the pressure and moldrolls to introduce skew to compensate for mold roll radial deflectionunder operating pressure.

[0036] By “radial deflection” as used herein, we mean any lateraldeflection of any portion of the axis of the roll, including bending orbowing deflections.

[0037] According to another aspect of the invention, an apparatus forcontinuously molding fastener elements integral with a base web includesa cylindrical mold hoop rotatable about an axis and having fastenerelement-shaped mold cavities in its peripheral surface. The apparatusalso has at least one driven roll arranged to engage an inner surface ofthe mold hoop to drive the hoop and a pressure-applying means arrangedto apply operating pressure to force the resin into said cavities at apressure zone.

[0038] In some embodiments of the apparatus of the invention, thepressure-applying means is constructed to apply first and secondoperating pressures at corresponding first and second said pressurezones at first and second mold gaps, respectively, with the mold roll.In some instances, the pressure-applying means comprises a nozzleassembly for introducing resin to the first pressure zone at the firstoperating pressure, the first mold gap comprising a gap between thenozzle assembly and the mold roll. In some cases, the pressure-applyingmeans also includes a pressure roll, the second mold gap comprising anip between the mold roll and pressure roll.

[0039] According to another aspect of the invention, a method ofcontinuously molding fastener elements on one broad side of a sheetproduct opposite another broad side having surface features, e.g.,raised or indented portions, is provided. The method comprises providingan apparatus that includes a mold roll, resiliently deformable pressureroll, and an extruder die, all as described above, passing a sheetproduct having the surface features through the nip with the moltenresin such that the resilient surface of the pressure roll conforms inthe vicinity of the features to protect the features as they passthrough the nip. The method also includes forming fastener elementsintegral with a base web on a broad side of the sheet product.

[0040] In some embodiments, an abrasive sheet product having moldedfastener elements on one side and abrasive particles on the other sideis formed by the in situ laminating method just described, in which thesurface features comprise abrasive particles.

[0041] In some embodiments the surface features comprise a decorativetexture such as an enclosed pattern or decorative fibers as in grasscloth. In some embodiments, the sheet product comprises a wall coveringcovered on its back side with fastener elements.

[0042] Various aspects of the invention disclosed here enablecost-effective commercialization of molded fastener products ofextremely wide widths and products having many very small fastenerelements. In particular, fastener products with very thin base layerthicknesses held to very close dimensional tolerances can be produced ina practical manner. According to another aspect of the invention, thecontact from loading systems that are provided according to theinvention in the form of load rolls or load belts, are advantageouslyemployed to extract heat from the back of the base layer of the product,to enable production of thicker base layers or to produce a product witha given base thickness at a much higher production speed than haspreviously been possible.

[0043] As will be understood from the foregoing and the remainingdescription and drawings, various features of the different aspects ofthe invention may be advantageously combined in other embodiments forcertain applications.

BRIEF DESCRIPTION OF THE DRAWINGS

[0044]FIG. 1 shows a molding system with a conformable load rollaccording to the invention.

[0045]FIG. 1A shows a molding system similar to FIG. 1 with anon-conformable load roll.

[0046]FIG. 2 illustrates the use of twin conformable load rolls.

[0047]FIG. 3 shows a molding system with a load belt.

[0048] FIGS. 4-6 show various methods of cooling a load roll. (FIGS. 5and 6 employ cooling belts).

[0049]FIG. 7 is an enlarged view of the contact zone between the loadroll and mold roll of FIG. 1.

[0050]FIGS. 7A and 7B illustrate different conformable load rollconstructions.

[0051]FIG. 7C is an enlarged diagrammatic view of a thermallyconductive, conformable material.

[0052]FIG. 8 illustrates the use of a series of adjustable load rolls.

[0053]FIG. 9 shows a molding system having two conformable load rolls.

[0054]FIG. 10 is an enlarged view of the molding nip between a mold rolland a conformable pressure roll.

[0055]FIG. 11 illustrates a construction of the conformable pressureroll of FIG. 10.

[0056]FIGS. 12 and 12A show inducing a curvature in, respectively, asolid and stacked-plate roll.

[0057]FIG. 13 illustrates skewing a pressure roll.

[0058]FIG. 13A is a bottom view of the skewed rolls, taken fromdirection 13A-13A in FIG. 13.

[0059]FIG. 13B illustrates an open-loop control system for skewing apressure roll.

[0060]FIG. 13C illustrates a closed-loop control system for skewing andloading a pressure roll.

[0061]FIG. 14 shows a system employing skewing and gross load control.

[0062]FIG. 15 illustrates the use of a cooling belt for a moldingsystem.

[0063]FIG. 16 shows a twin molding nip arrangement, according to theinvention.

[0064]FIGS. 17, 17A and 18 through 21 illustrate methods and systems forforming a laminate product.

[0065]FIGS. 22 and 23 illustrate systems employing a pressure head and aconformable loading system.

[0066]FIG. 24 shows a system with a pressure head and a cooled,conformable load roll.

[0067]FIGS. 25 and 26 show control systems for systems with pressureheads.

[0068]FIG. 27 is of a dual pressure head system.

[0069]FIGS. 28 and 29 illustrate laminating in a pressure head system.

[0070]FIGS. 30A through 30C illustrate cross-sections of fastenerproducts.

[0071]FIG. 31 shows an embodiment useful for molding fastener elementson a backing material.

[0072]FIG. 32 is an enlarged view of part of the nip of FIG. 31,illustrating an effect of a compliant pressure roll.

[0073]FIGS. 33 and 34 illustrate systems employing a pressure roll and apressure head.

[0074]FIG. 35 shows a system with a mold hoop.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0075] Referring to the embodiment of FIG. 1, an extruder 4 delivers awide extrusion of molten polymer 100 into the nip (i.e. into thepressure zone) between an elongated mold roll 1 and a pressure roll 2.The polymer is forced into fastener-shaped cavities 102 by the pressureof the nip, forming a base layer with integral fastener elements. Thefastener elements are, in some cases, fully-formed elements capable ofsnagging loops as molded. In other cases, the fastener elements arepreform elements that are intended to be subjected to a post-formingoperation to form completed fastener elements. The post-formingoperation, in some cases, forms flat top portions on hook or postpreforms. The fastener elements are very small to engage small loops orfibers on a surface, and typically are arranged on the web base with adensity of 500 to 2,000 fastener elements per square inch.

[0076] The fastener product 5 is carried on the chilled mold roll 1 adistance sufficient to solidify the fastener elements before removingthe elements from their mold cavities 102. A take-off roll 6 is employedto peel the fastener product 5 from mold roll 1. Typically the nippressure is controlled by actuators (not shown) that force pressure roll2 against mold roll 1.

[0077] A load roll 3, on the side of mold roll 1 opposite to the side ofthe pressure zone, is arranged to engage mold roll 1 to resist thebending of mold,roll 1 that would otherwise occur due to pressure zoneforces. By “engage” we mean that the load roll 3 either directlycontacts the load roll surface or resin or other product layer on thesurface of the load roll, with a substantial contact force. The forceexerted by load roll 3 against mold roll 1 is controlled by a controlsystem 7. Control system 7 varies the position of the load roll tocontrol the load applied to mold roll 1 to result in a more uniformproduct base layer thickness, and to protect against accidental contactbetween the mold roll and pressure roll. The load applied by the loadroll to mold roll 1 is preferably about the same as the load appliedagainst the mold roll by pressure roll 2.

[0078] In a preferred embodiment, load roll 3 (a support roll) has aresilient external layer of thickness t (shown exaggerated in thefigure), such as 0.5 inch of urethane elastomer. The compliance of therelatively soft external layer of load roll 3 results in a relativelywide contact area 106 between load roll 3 and mold roll 1 and loweraverage contact pressures than the pressure in the nip between mold roll1 and pressure roll 2. It also provides more uniform load distributionalong the axis of the roll, compensating for small radial deflections ofrolls 1 and 2. The relatively low contact pressure avoids damage to thedelicate mold surface (e.g. coining or fatigue in the region of the moldcavities) that would result from high pressure, direct contact with ahard load roll. The integration of the component of this contactpressure parallel to the plane of the axes of the mold and pressurerolls 1 and 2 provides a reaction force to balance the bending forceapplied to mold roll 1 by nip pressure. Load roll 3 is preferablyconstructed and arranged to provide a reaction load substantially equalto the bending load from the pressure zone, thereby maintaining thestraightness of mold roll 1, and the uniformity of the gap along thelength of the rolls.

[0079] Control system 7 responds to the thickness of the base layer ofthe product while on the mold roll, as measured by thickness sensor 13,and adjusts the reaction load applied by load roll 3 accordingly. In analternative embodiment, sensor 13 is replaced by a means to measure thedistance between rolls 1 and 2.

[0080] Also shown in FIG. 1, in dashed lines, is an alternativeplacement for the take-off roll, shown as take-off roll 6 a. In thisalternative embodiment, the product as it cools is carried by mold roll1 through a second nip between the mold roll and load roll 3, and issubsequently peeled away by take-off roll 6 a as fastener product 5 a.This alternative embodiment is especially useful when longer coolingtimes are desired, as it enables the cooling fastener product to becarried by chilled mold roll 1 for a longer time to conduct more heatfrom the product. Leaving the product in the mold cavities duringcontact with load roll 3 also can provide important protection to themold cavities from damage when high loading pressures are employed, aswith rolls having a hard outer layer. In embodiments where load roll 3is cooled, e.g. by controlled flow of coolant through its interior,additional heat is advantageously extracted from the back side of theproduct as it passes through the second nip. The relatively wide contactarea between mold roll 1 and load roll 3 can help to promote this heattransfer.

[0081] The machine and process shown in solid lines in FIG. 1 are usefulwhen molding delicate products that may tend to be damaged fromtravelling through the second nip, whereas the machine and process shownin dashed lines is useful for more rugged products and for high speedproduction.

[0082] As shown in FIG. 1A, passing the cooling product through the nipbetween mold roll 1 and load roll 3′ enables, in another embodiment, theuse of a non-conformable load roll 3′. In this embodiment the presenceof the resin in the cavities and between the load roll and the mold rollprovides important protection to the surface of the mold roll and themold cavities. Without the product present in the nip between the moldroll and the load roll, the features of the surface of the mold roll(e.g. mold cavities 102) would be susceptible to damage from highcontact or Hertzian stresses, which can be hundreds of thousands ofpounds per square inch. These high contact stresses can, for instance,deform the mold roll surface plastically such as by coining orflattening the tips of some of the fastener-shaped cavities. Even if themold roll surface is not deformed instantly, the repeated, localizedstress applied to the metal forming the inside of a hook-shaped fastenerfrom such hard surface contact can cause fatigue and fracture, resultingin some of the hooks being deformed and the resulting product having anunattractive appearance.

[0083] Further features are provided to avoid applying a substantialload to mold roll 1 by hard load roll 3′ of FIG. 1A when there is notsufficient polymer product in the load roll nip to protect the moldcavities. In one case, thickness sensor 13 is adapted to detect aninterruption in the flow of product. Control system 7 is adapted torespond by quickly unloading load roll 3′, thereby avoiding directcontact load against a bare mold roll.

[0084] In FIGS. 1 and 1A the axis of load roll 3 or 3′ was substantiallyin the plane of the axes of mold roll 1 and pressure roll 2, all threeaxes being substantially parallel.

[0085] Referring to FIG. 2, another embodiment has two load rolls 3 aand 3 b that are generally opposite the pressure zone between mold roll1 and the pressure roll, but whose axes are out of the plane of the moldroll and pressure roll. Load rolls 3 a and 3 b are shown to bepreferably arranged in a symmetric or balanced manner about the planedefined by the axis of the upper rolls. The axes of load rolls 3 a and 3b are parallel with each other and substantially parallel with the axesof the upper rolls. This double load roll arrangement advantageouslyresults in an even larger net contact area against mold roll 1 and evenlower average contact pressure.

[0086] Referring back to FIG. 1, one embodiment of the control systememploys manual adjustment by the operator of the pressure applied byload roll 3. At start up, a release paper is passed with the extrudedpolymer through the nip between mold roll 1 and pressure roll 2, thepaper covering cavities 102 so that the initial melt from the extruderdoes not enter the cavities. The release paper continues to pass throughthe nip until the surface of mold roll 1 and cavities 102 reach anappropriate operating temperature and speed. At this point, because ofthe presence of the release paper covering the cavities, the product 5or 5 a has no fastener elements. When operating conditions are reached,but before applying substantial pressure from either pressure roll 2 orload roll 3, entry of the release paper into the nip is discontinued,exposing cavities 102 to the molten polymer, which begins to flow intothe cavities to form partial fastener elements. The load betweenpressure roll 2 and mold roll 1 is then increased by moving the pressureroll closer to the mold roll until there is enough pressure developed onthe melt to completely fill cavities 102 under the desired conditions.At this point, fastener product 5 or 5 a has useful, fully-formedfastener elements integrally molded with the base layer, although theuniformity of the product is affected by the longitudinal bending ofmold roll 1, resulting in a base layer that is typically thicker in themiddle of the product than on the edges. While measuring the thicknessof the base layer (e.g. by thickness sensor 13), the loads applied bypressure roll 2 and load roll 3 are increased until a desirable productis produced.

[0087] In a typical operation the load applied by pressure roll 2 isadjusted to produce the desired average or mean product base thickness,and the load applied by load roll 3 is adjusted to reduce base thicknessvariation across the width of the product.

[0088] In such an arrangement the mold roll may be two feet or longer inlength and the load applied by the pressure rolls may be as much as 1600pounds or more per lineal inch of mold nip.

[0089] In a more complex control system 7, signals from thickness sensor13 (or multiple sensors arranged to sense various desired controlparameters) are fed into an electronic controller that contains analgorithm that controls the loading forces or roll displacements toproduce a desired product. Thickness sensor 13 is, in the presentlypreferred embodiment, a magnetic reluctance sensor placed, as shown, todetect base layer thickness near the pressure zone. Alternatively,sensor 13 (in the form, e.g., of a beta-gauge) may be placed downstreamof the mold apparatus. In some situations it is desirable to use ascanning sensor 13 that traverses the width of the product and measuresvariation in base thickness across the width. If load roll 3 has asufficiently compliant surface and is adjusted to completely balance theload applied by a sufficiently stiff pressure roll 2, a stationarythickness sensor 13 measuring the thickness at one point along the widthof the product may provide sufficient control feedback, due to thepressure nip gap remaining even. If the pressure roll is approximatelyas flexible as the mold roll, more load must be applied by the load rollto compensate for the bending of the pressure roll to maintain an evennip gap by bowing the middle of the mold roll toward the bowed pressureroll. The stacked plate structure of the mold roll, however, limits theamount of forced curvature that can be tolerated before adjacent platesof the mold roll begin to separate and cause molding flash. Extremeaxial loading of the mold roll (e.g. by tie rods) can extend this limitand increase the amount of mold roll curvature that can be tolerated.Furthermore, pressure roll 2 is more readily constructed to be rigid inbending to address this condition than is the mold roll.

[0090] Referring to FIG. 3, in another embodiment a load belt system 108replaces load roll 3 of FIG. 1 as the means to apply a reaction load tomold roll 1 to balance the load applied by pressure roll 2. Load beltsystem 108 has a load belt 14 and at least two or more rolls 110 totension and support belt 14. Belt system 108 is loaded against mold roll1 effectively in the plane of the axes of the mold and pressure rolls.

[0091] An advantage of using a load belt system 108 is that the contactload against mold roll 1 is spread over a very wide contact area to makethe contact pressure low. In addition, by the provision of cooling fluidas suggested by arrow A, effective cooling is achievable. In the case ofthe arrangement shown in dashed lines in FIG. 3, contact with thecooling product occurs over a long length of travel so that even at highspeed there is time to extract heat from the back side of the base layeras it passes between load belt 14 and the mold roll.

[0092] FIGS. 4-6 show a number of ways, according to the invention, tocool the molding system. To advantageously remove heat at a constantrate from either the product or mold roll 1 by a conformable load roll3, heat is continuously extracted. Due to the relatively low thermaltransfer characteristics of most durable, highly compliant materials (ascompared to metals), in most instances it is preferable to transfer heatdirectly from the load roll surface rather than transfer it through theouter compliant layer of the load roll to an internal cooling system.Cooling the load roll also reduces the amount of heat that otherwise hasto diffuse through the tooling rings or disks of the mold roll to beextracted by a heat removal means such as circulated water in the coreof the mold roll. This reduces the temperature gradient between thesurface of the mold roll and the cooled core of the mold roll, which, inturn, improves the assemblability of the mold roll and helps to keep themold rings in contact with the central mold roll shaft, in part becausedifferences in thermal expansion of the components of the mold roll arereduced due to reduced temperature gradients.

[0093] In FIG. 4, cold air is blown across the surface of the load rollfrom a cold air source 112. In FIG. 5 a moving cooling belt 114 is heldin contact with load roll 3. Cooling water (represented by block 116) issprayed against the back side of thermally conductive belt 114, whichtransfers heat from the surface of load roll 3. Belt 14 shields loadroll 3 from the cooling water, helping to keep the product dry.

[0094] As shown in FIG. 6, an alternative arrangement is to run coolingbelt 114 through the load roll nip. In the case where the productremains on mold roll 1 and is peeled off after passing through the loadroll nip (i.e. by take-off roll 6 a in FIG. 1), belt 114 is passedthrough the load roll nip along with the cooling product. Thisarrangement is particularly useful for rapid cooling of the back side ofthe base layer, as cooling belt 114 is held in direct contact with theproduct through the entire contact area of the load roll nip. Belt 114may in turn be cooled (e.g. by water 116 or air) at some distance fromthe nip.

[0095] Referring to FIGS. 7 and 7A, in the presently preferredembodiment conformable load roll 3 has a stiff, relativelynon-conformable core 72 (preferably steel), a compliant layer 74(preferably an elastomer), and an outer sleeve 76 which is formed of anelastically deformable material with a hard surface, preferably eitherhard polymer or metal. In the present embodiment, the overall diameterof load roll 3 is about 12 inches and compliant layer 74 has a thicknesst of about 0.5 inch. A suitable material for compliant layer 74 isurethane, due to its stability, its ability to be sized by grinding, andits relatively low cost. For higher temperatures, silicone rubber isalso acceptable. Outer sleeve 76 preferably has a smooth exterior andhas a high thermal conductivity to remove heat either out of the backside of a product with a relatively thick base layer or directly out ofthe mold roll itself. Under some temperature and speed conditions,sleeve 76 may be omitted.

[0096] Referring to FIG. 7B, an alternative embodiment of conformableload roll 3 is pneumatically inflatable, such as an automobile tire. Asin a tire, a steel reinforcement belt 71 is preferably employed tostiffen and extend the life of the load roll.

[0097] Referring to FIG. 7C, in other embodiments designed to conductheat through a compliant layer of a roll (e.g. load roll 3 of FIG. 1)particles 80 and 82 of thermally conductive materials are molded intocompliant material 74. Materials such as powdered aluminum, carbon orpowdered copper raise the effective thermal conductivity of a compliantlayer that otherwise consists of polymers having relatively low thermalconductivity. In general, a dense distribution of a mixture ofrod-shaped particles 82 and spherical particles 80 provides a higherthermal conductivity at the same volumetric loading ratio than either ofthe shapes alone. This construction is also useful to form the coolingbelts of FIGS. 5 and 6.

[0098] The load roll 3 or 3′ (or rolls 3 a and 3 b) of the precedingfigures is (are) configured, in some embodiments, as a series ofindependently controllable rolls 120 arranged along the length of themold roll, as shown in FIG. 8. Mounted on separate shafts, load rolls120 a, 120 b and 120 c are loaded independently against mold roll 1 tomaintain a constant, even gap between the mold roll and the pressureroll to produce an even thickness product. Instead of relying on thepassive conformability of the load roll to maintain gap uniformity, thisembodiment enables active control of gap thickness at distinct pointsalong the width of the product. For instance, the load roll or rolls 120near the middle of the span of the mold roll can be employed to apply ahigher load than the rolls 120 near the edges, if required to optimizeor minimize the curvature of the mold roll. The configuration of FIG. 8is particularly applicable for use with a relatively long mold roll 1 orwhen extremely precise gap control is required. Preferably there is atleast one thickness sensor 13 (FIG. 1) associated with each load roll120.

[0099] Referring to FIG. 9, in another embodiment a conformable roll122, of similar construction to that previously discussed for load roll3, is arranged to load against the back side of pressure roll 2 oppositemold roll 1. Conformable roll 122 maintains a desirable degree ofcurvature (or lack thereof) in pressure roll 2 to control the gap at thepressure zone between pressure roll 2 and mold roll 1. The compliance ofconformable roll 122 reduces the chance of surface fatigue damage thatmight be caused by two hard rolls rolling against each other, and alsoallows a slight curvature of pressure roll 2 in some instances wherethat is desired. As shown with respect to load roll 3 in FIG. 8,conformable pressure backup roll 122 can be configured as multiple rolls120.

[0100] Referring to FIG. 10, in some embodiments it is desirable toconstruct pressure roll 2′ with some compliance. FIG. 10 illustrates anenlarged cross section of the pressure zone between mold roll 1 (withcavities 102) and pressure roll 2′, which forces melt 100 into cavities102 and counteracts the pressure of forming base layer 124 of the moldedfastener product. High pressures are developed, illustrated by pressuredistribution curve 126, that push melt 100 into cavities 102. At higherproduction speeds the compliance of pressure roll 2′ results in a widerpressure zone area, increasing the length of time that a given portionof melt is subjected to elevated molding pressures.

[0101] As shown in FIG. 11, pressure roll 2′ preferably has a relativelyhard and rigid surface layer, such as a metal sleeve 128, covering asofter, more compliant layer 130. Compliant layer 130 in someembodiments is an elastomeric material, and in other embodiments is afluid under pressure.

[0102] In some embodiments it is desirable to actively bend a rotatingroll to create radial deflection. FIGS. 12 and 12A, for instance,illustrate a method for applying a controllable bending moment to a rollusing secondary bearings or supports 132 a and 132 b. This is useful,for example, to deform pressure roll 2 to match the curvature of themold roll. Spherical journal bearings that allow a small degree ofangular deflection of the shaft of the roll are suitable for the outersupport bearings 134 a and 134 b. Between outer bearings 134 a and 134b, secondary supports 132 a and 132 b bear against the roll and producea constant bending moment between the secondary supports. Secondarysupports 132 a and 132 b are, in some cases, large diameter bearingsthat are nearly the same diameter as the central portion of the roll. Inother cases fluid film bearings or other rollers are employed to bear onthe surface of the roll.

[0103]FIG. 12A illustrates this bending technique employed to bend amold roll 1 comprised of stacked plates or rings. This active bendinghelps provide compression between the faces of the tool rings where themelt is formed into fastener elements, squeezing the tool rings togetherto avoid producing molding flash between them. The molding region L ofthe mold roll is that part of the roll comprised of mold plates withmolding cavities or which otherwise forms the molding surface of theroll.

[0104]FIGS. 13 and 13A illustrate another method and system forcontrolling the thickness of the molded fastener product base layer whenmold roll 1 is relatively long and therefore tends to deflect under thepressure of the pressure zone. In operation, nip pressure between thetwo rolls tends to cause mold roll 1 to move away from pressure roll 2in a bowed manner, causing the nip gap to be greater near the middle ofthe span than near the ends, forming a product base layer that isundesirably thicker at its midspan than at its edges. In order tocompensate for this, the axis of pressure roll 2 is controllably skewedrelative to the axis of mold roll 1, to provide a more uniform nip gapalong the mold roll. Controller 90 controls the amount of skew. Byproper adjustment of the skew angle a over a practical range, the gapcan be made essentially constant along the length of the nip despitepressure-induced radial deflection of the mold roll.

[0105] A control method employing an “open” control loop is illustratedin FIG. 13B. The control technique is called open-loop because theoperator 150 sets the skew between the left and right sides of pressureroll 2 based on a signal from a downstream device 40. In the presentconfiguration, device 40 is a Beta-gauge mass sensing device to senseproduct base layer thickness and thickness variation across the web. Inoperation, operator 150 adjusts left and right skew settings on controlpanel 42, providing the command signals to servo controller 44 whichcontrols left and right ball screws 48. Feedback 50 from ball screws 48to servo controller 44 informs the servo controller of the currentposition of the ball screws. Thus the actual skew position isclosed-loop, PID (Proportional/Integral/Differential) controlled insidethe servo loop, but the position set point is adjusted by an operator.

[0106] In another embodiment illustrated in FIG. 13C, a systemcontroller 52 replaces the operator for closed-loop control of thesystem. System controller 52 determines the desired amount of skew toproduce a constant base layer thickness and produces a command signalfor the ball screw servo controller 44. The system controller also sendscommand signals to a hydraulic servo controller 58 that controls theposition of left and right hydraulic load actuators 152. The hydraulicload actuators adjust the overall position of pressure roll 2 to providea desired average base layer thickness with minimal variation from oneedge to the other.

[0107] The Beta-gauge 40 is a relatively slow method of measurement. Itis a scanning system which travels across the product at about 3 to 4inches per second, and in one embodiment is located about 20 secondsdownstream from the nip. The thickness feedback is therefore delayed bythe time required for the product to travel to gauge 40 and by the timerequired for the scanning operation of the sensor. Any corrections madeby controller 52 therefore need to be based on average trends to avoidinstabilities caused by immediate real time correction.

[0108] Alternatively, the thickness of the base layer of the product canbe sensed in close proximity to the nip, e.g. by sensor 13. Preferablysensor 13 is a non-contacting sensor (e.g. a reluctance sensor floatingon a gas film bearing on the base layer), but sensing mechanisms heldagainst the back of the product with light pressure are also suitable.

[0109] Referring to FIG. 14, a preferred embodiment provides a usefulcombination of control techniques, including skew control, formaintaining constant base layer thickness. Gross (average) thicknesscontrol is provided by a control system 140 controlling the normal loadbetween mold roll 1 and load roll 3. Fine thickness control is providedby control system 142 operating actuators at each end of pressure roll 2(to adjust for left/right unevenness) and the skew of pressure roll 2(to adjust for middle/edge unevenness). Such combinations are usefulwhen skewing alone requires impractically large skew angles. Bycompensating for most variation with gross variation control system 140,skewing is only necessary for fine control for automated trimming ofthickness across the width of the product.

[0110] Referring to FIG. 15, a cooling belt 160, similar to the belt 114shown in FIGS. 5 and 6, is useful in some embodiments to cool andsupport the fastener product through the continuous molding process. Asillustrated, belt 160 is introduced to the nip between mold roll 1 andpressure roll 2 along with the melt 100. Belt 160 remains in contactwith the cooling product as it is carried about the mold roll, helpingto draw heat out of the base layer and maintaining continuous pressureagainst the back side of the product. The belt continues through thesecond nip, between load roll 3 and mold roll 1, and provides additionalsupport for the product as it is peeled off of the mold roll by take-offroll 6. After passing through a third nip between load roll 3 andknock-down roll 162, belt 160 is peeled away from product 5.

[0111] The embodiment of FIG. 15 is particularly useful for very fastproduction speeds, as the prolonged contact between the product and belt160 helps to cool the base layer, so that the product can be quicklypeeled from the mold, without sufficiently cooling the fastener elementsto the point that they can no longer be easily deformed for removal fromthe mold cavities.

[0112] Referring to FIG. 16, in some particularly useful embodiments twocontinuous streams of fastener product are simultaneously manufacturedwith a single mold roll. Mold roll 1 is arranged between pressure rolls2 and 2 a, defining two pressure zones. Twin extruders 4 and 4 a supplymolten resin to the two pressure zones, and the molded product is peeledaway from mold roll 1 by two take-off rolls 170 and 170 a. Arranging theaxes of mold roll 1 and pressure rolls 2 and 2 a to lie in substantiallythe same plane balances the nip pressure loads exerted on mold roll 1,greatly reducing the tendency of the mold roll to bend. Any of themethods previously discussed may be employed, if necessary, to reducebending of pressure rolls 2 and 2 a or to otherwise maintain theevenness of the pressure zone gaps. Belt systems 108, as illustrated inFIG. 3, are useful in place of hard or compliant pressure rolls.

[0113] One of the advantages of having two, balanced pressure zones onthe same roll, as shown in FIG. 16, is that the amount of productproducible from a single mold roll can be significantly increased.Another advantage is that the loads on the mold roll are balanced,enabling less expensive mold roll structures with lower stiffnessrequirements. Yet another advantage is that it enables the production ofwider fastener products (i.e. by allowing the use of longer mold rolls)without compromising the evenness of product base layer thickness orproduct quality.

[0114] Referring to FIG. 17, in some useful embodiments an addedmaterial 9 is introduced to a second nip between mold roll 1 and loadroll 3 to form a laminate product 5c with molded fastener elements onone side and added material 9 on the other. It is advantageous that thisis done on the mold roll while the fastener elements remain protectedfrom laminating pressure by remaining in their respective cavities.Preceding the laminating action the back side of the fastener product isre-softened, if necessary, by a heat source 10 to enhance the adherenceof the base layer to the added material 9 in the second nip. Addedmaterial 9 is introduced with the molded fastener product into thesecond nip, which in some embodiments is defined by a compliant loadroll 3. Following the laminating nip, the molded product is carriedaround a substantial arc of the mold roll and cools to the appropriatetemperature to set the bond to the added material. The resultinglaminate is removed from the mold roll by a take-off roll 6 a. Bybonding the added material to the fastener product while the latter isstill being carried on the mold roll, the laminate is formed with thebase layer advantageously in a heat-softened, clean condition, resultingin a sound bond. The freshly molded base layer provides a very goodsurface for adhering the added material to form a laminate. In addition,the product base layer is substantially supported between fastenerelements by the surface of the mold roll, allowing higher locallaminating pressures to be employed without deforming the fastenerelements. This arrangement enables the laminating of fastener productswith relatively thick added materials that are very difficult to passthrough the pressure zone (i.e. between mold roll 1 and pressure roll 2)without disrupting the molding process.

[0115] The embodiment of FIG. 17A is similar to that of FIG. 17 exceptthat the load roll 3 that provides the nip where lamination is performedis a hard roll instead of a compliant one.

[0116] Examples of laminate products that are suitable to being formedin this manner include carpets and wall coverings. The second nip(laminating nip) may be maintained at more suitable temperatures and/orpressures to prevent damaging such products that would not reliablywithstand passage through the molding nip. Furthermore, theconformability of load roll 3 helps to protect relatively delicatesurface formations (of, e.g., a wall covering) from undesirabledeformation during laminating.

[0117] Referring to FIG. 18, other methods of bonding added material 9to form a laminate material 11 with a molded fastener product includethe application of an adhesive with an applicator 12. Suitable methodsfor applying the adhesive include spraying it directly on added material9 or the back side of the unlaminated base layer prior to the laminatingnip, coating the side of added material 9 with a film layer of adhesivein a previous process, rolling, doctoring and the like.

[0118]FIG. 19 shows a variation to the lamination method employing abelt 172 that carries added material 9 into and through the laminatingnip between load roll 3 and mold roll 1. Belt 172 provides extra supportfor the added material on the way into the nip and also can provideeither heating or cooling, depending upon whether the belt is heated orcooled. In some embodiments the belt surface is metallic and ofdifferent consistency from the compliant layer on the load roll. Thismachine and process is useful for laminating heavy web materials such asfloor mat material and the like.

[0119]FIG. 20 shows another arrangement useful for forming a laminateproduct, employing a belt system 108 (as in FIG. 3) to providelaminating pressure. Belt system 108 conducts a belt 14 in close contactwith mold roll 1. Both the belt and its roller system are forced upagainst the mold roll to provide sufficient pressure for lamination.This method is most advantageous for laminations requiring a long time(i.e. a wide contact area in this embodiment) for proper bonding.Another advantage of employing a belt system to provide laminationpressure is that microscopic scuffing of a compliant roll against a hardsurface that might damage delicate laminate materials, such as paper orvinyl wall coverings, is avoided, without the high contact pressures ofa hard load roll. The laminated product is either removed with the beltsystem or is carried further about the mold roll and peeled off by aseparate take-off roll 6 a. An optional cooling system is illustrated bybox 174.

[0120]FIG. 21 shows a combination of thickness control and lamination. Askew-controlled pressure roll 2 and controller 176 maintain a constantthickness of molded product base layer. As described in previousembodiments, load roll 3 compensates for the load applied by pressureroll 2, minimizing the bending of the mold roll and thereby minimizingthe amount of pressure roll skew necessary to maintain constant baselayer thickness. In addition, a second load roll 178 bears against loadroll 3, helping to maintain the straightness of load roll 3 and alsoproviding an additional pressure nip through which the laminate istrained for improved bonding.

[0121] FIGS. 22-29 illustrate other configurations, equally as useful asthose thus far described, that employ a pressure head 8 fed by anextruder or other source of pressurized molten polymer resin to bothintroduce the molten resin that will form the molded fastener productand to apply the pressure necessary to force the resin into thefastener-shaped mold cavities. As illustrated by the common referencenumbers in these figures and earlier figures, other components of thesystems that employ a pressure head 8 are essentially the same as thoseemploying a pressure roll 2. These additional figures show that thenovel features described with reference to a system with a pressure rollapply equally as well to a system with the pressure head 8. In thisrespect, the previous descriptions of the figures to which FIGS. 22-29correspond are also applicable to these embodiments. FIG. 22 correspondsto FIG. 1, FIG. 23 to FIG. 3, FIG. 24 to FIG. 4, FIG. 27 to FIG. 16,FIG. 28 to FIGS. 17, 18 and 19, and FIG. 29 to FIG. 20. From theseexamples it should be evident that any of the other embodimentsheretofore disclosed may be adapted to employ a pressure head.

[0122] Pressure head 8 in FIGS. 22-29 comprises an extruder nozzleassembly fed by an extruder (not shown). In nozzle throat 8 a a sheetform flow of polymer is produced, which is applied to the mold roll 1.Shoe surfaces 8b of the nozzle assembly that conform to the curvature ofthe roll serve to maintain the extruder pressure against the roll and todefine the gap with the mold roll that defines the thickness of the baselayer of the product. Pressure head 8 thus forces the polymer into themold cavities in mold roll 1 and forms a sheet-form film or base layerof polymer on the surface of the mold roll. As in the previousembodiments, the polymer is forced into the mold cavities to formfastener elements or the like under the high pressure of the pressurezone. The pressure zone forces tend to bend the mold roll away from thepressure head and are resisted by the methods described above (with,e.g. a compliant load roll 3 as in FIG. 22 or a belt system 108 as inFIG. 23) to maintain an even gap for forming the base layer of thefastener product.

[0123] Referring to FIG. 25, an arrangement for controlling the gapbetween mold roll 1 and pressure head 8 actively adjusts the shape andposition of the pressure head relative to the mold roll. This can bedone, for instance, in response to thickness sensor 13. The axis of moldroll 1 is supported on suitable bearings (not shown) in a load frame 60.An extension 60 a of load frame 60 supports a head loading system 180(e.g. a number of hydraulic cylinders or ball screw actuators arrangedalong the length of the pressure head). Molten polymer resin is suppliedby a melt source or extruder 61 to head 8 under pressure. Head loadingsystem 180 loads head 8, by shafts 62, against mold roll 1 through afilm of molten resin, thereby maintaining a controllably constant gapbetween mold roll 1 and head 8 for forming the base layer of thefastener product 5.

[0124] For active bending of the pressure head 8 to contour the surfaceof the pressure head along its length to conform to the surface geometryof the bent mold roll, other means of bending pressure head 8 include anumber of tie bolts between the molding head and frame 60, arrangedalong the length of the pressure head, that are axially adjusted eitherby rotating a threaded member or by controlled thermal expansion (i.e.changing the net length of the tie bolts by changing their temperature).Adjusting the lengths of individual tie bolts induces bending moments inpressure head 8 that causes its curved surface 182 to also bend alongits length to conform to the curvature of the mold roll.

[0125] Under some circumstances it is desirable for mold roll 1 to beslightly elastically bent away from pressure head 8 (or pressure roll 2)by pressure zone forces to increase the axial compression between thestacked mold plates that form the mold roll in the vicinity of the highpressure zone. This can reduce the tendency of the molten resin to formflash between the mold plates. In these instances it is advantageous tohave some intentional bending of the mold roll away from the pressuresource, and to force the pressure mechanism (e.g., pressure head 8 orpressure roll 2) to follow that curvature in order to maintain theuniformity of the gap and of the product. Referring further to FIG. 25,the load system 180, comprised of several loading rods 62 distributedalong the length of the pressure head, forces head 8 toward mold roll 1near its midspan to compensate for the curvature of the mold roll. Rods62 are individually controlled by a control system to locally forcepressure head 8 toward or away from mold roll 1 to maintain the desiredgap. This technique is particularly useful to mold extremely wide widthsof product by compensating for the increased bending of relativelylonger rolls subjected to higher overall mold pressure forces.

[0126] In some instances it is desirable not to have a perfectly evengap across the width of the pressure zone. For instance, in some casesit is desirable to have the gap slightly smaller toward the edges thanin the middle, for example when there tends to be some leakage ofpolymer material from the edges of the pressure zone.

[0127] Referring to FIG. 26, use of a load roll 3 with a pressure head 8is presently preferred to avoid extreme mold roll curvature insituations where the flatness of the product is critical. Molding theproduct on a bowed mold roll results in a base layer that has a degreeof complex curvature, even after being spooled. In some cases such acurvature is desirable, but in others it is not. Some preferredembodiments therefore employ both pressure head curvature control and aload roll on the side of the mold roll opposite the pressure head.Controller 182 controls the relative positions of load roll 3 andpressure head 8 with respect to mold roll 1. Displacement transducers184 and 186 and thickness sensor 13 provide feedback. In the embodimentshown, controller 182 controls force F₂ which loads frame 188, to whichboth mold roll 1 and load roll 3 are mounted, toward head 8. Inaddition, controller 182 controls force F₁ which forces load roll 3against mold roll 1.

[0128] As shown in FIG. 27, a particularly advantageous embodimentemploys two relatively stiff pressure heads 8 supplying molten resin totwo pressure zones on opposite sides of a single mold roll 1. Thisproduces two continuous streams of product 5 and 5′ that are peeled frommold roll 1 by take-off rolls 6 and 6′, respectively. For the reasonsalready described, extremely wide widths of a thin, even product arethus moldable, due to the balance of forces acting on relatively longmold roll 1.

[0129] FIGS. 30A-30C illustrate some of the web base thickness profilesthat can be maintained by the apparatus and method of the presentinvention, shown in cross-section across a portion of the length of themold roll. In FIG. 30A, fastener product 5 has a base web 200 andmultiple upstanding fastener elements 202. Maintaining the thickness ofthe mold gap that forms base web 200 along its length produces a product5 with a base web 200 of generally consistent thickness t. In anotherembodiment, shown in FIG. 30B, tapered regions 204 are provided in thepredetermined profile of base web 200. In some cases, grooves 206 orother indentations are formed in base web 200, as shown in FIG. 30C.These and other profiles are advantageously maintained at theirpredetermined thicknesses by maintaining the profile of the mold gap asdescribed above.

[0130] Referring to FIG. 31, in another embodiment a compliant pressureroll 2′ is employed to protect surface features on the surface of asheet material 210 introduced to the molding nip between pressure roll2′ and mold roll 1. These surface features would tend to be damaged bybeing passed through a nip formed by two non-conformable rolls. Hardsurface features can also damage non-conformable roll surfaces. Thisarrangement is particularly useful, according to the invention, forcontinuous molding of fastener elements on one side of a sandpaperproduct having surface features consisting of grains of sand or otherabrasive particles adhered to one broad surface of the paper. It is alsouseful for molding fastener elements on wide sheets of material havingdelicate surface features, such as fibers or embossed features, thatcould be damaged by the extreme pressures of the molding nip. Examplesof these types of materials include upholstery material withleatherette-grained surfaces and grass-paper wall coverings. Aftermolding, the finished product is pulled from the mold cavities of moldroll 1 about a take-off roll 211, which also has a compliant outersurface.

[0131]FIG. 32, looking in the direction of the flow of material throughthe mold nip between compliant pressure roll 2′ and mold roll 1,illustrates the deformation of the surface of the pressure roll in thevicinity of abrasive grains 212 as a sandpaper product 214 is passedthrough the nip. Abrasive grains 212 are quite small in most commercialsandpapers, which have grades from 30 to over 600 for fine polishingapplications. The compliant surface of pressure roll 2′, preferably ofan elastomeric material of 60 to 70 durometer for use with a medium-gritsandpaper, conforms to encapsulate the grains 212 and distributepressure around the grains. Because there is effectively no surfacespeed differential between rolls 1 and 2′, grains 212 do not abrade theelastomeric surface of roll 2′. The resulting abrasive product is “insitu laminated” to fastener elements such as hooks for hook to loopfastening. In other words, the forming of the base web integral withfastener elements and the lamination of the base web and abrasive paperoccur simultaneously in the nip. The resin of the base web is laminatedto the back of the sandpaper to provide a means for fastening thesandpaper to a sanding block or other sanding device.

[0132] Referring to the molding system of FIG. 33, in some cases thesystem has both a pressure head 8′ and a pressure roll 2. The pressurehead 8′ preferably applies sufficient pressure in pressure zone P₁ topartially fill the fastener element cavities in mold roll 1 and providea layer of resin on the exterior of the mold roll. Pressure roll 2provides a second application of pressure against the resin in anotherpressure zone P₂, with the resin still in a formable condition, tocomplete the filling of the cavities in the mold roll and produce a baseweb with even thickness. Surface 8 b′ of pressure head 8′ is curved tomatch the curvature of the mold roll. For molding systems with twopressure zones P₁ and P₂, support roll 3 is preferably arranged tocounteract the loads against the mold roll from both pressure zones(i.e., the three rolls 1, 2 and 3 do not lie in a single plane). Byapplying the resin directly against the mold roll, temperaturevariations and edge shrinkage can be minimized while, by subsequentlyemploying the pressure roll, uniform filling of the mold cavities can beassured under, e.g., high speed conditions.

[0133] Referring to FIG. 34, in some instances a pressure head 8″extrudes resin directly onto the surface of a pressure roll 2. Theextruded resin enters the nip between pressure roll 2 and mold roll 1where it is forced under nip pressure to fill the cavities in the moldroll. In this case it is not necessary, in most situations, for thepressure head 8″ to apply substantial pressure, and therefore the threerolls 1, 2 and 3 are preferably coplanar.

[0134] Referring to FIG. 35, another molding system employs a mold hoop220 with fastener element cavities formed in its outer surface. The moldhoop is held against pressure roll 2 with a loading roll 222, forming amolding nip and pressure zone between hoop 220 and roll 2. Loading roll222 preferably has a conformable surface, as described above withreference to FIG. 1. Additional rolls 224 a and 224 b provide additionalsupport for hoop 220, which is driven by rotating rolls 2 and 222. Therelatively large diameter of hoop 220 provides room within the hoop forcooling systems 226 for cooling the hoop. This arrangement isparticularly suitable for molding conditions that require the coolingfastener elements to remain in their cavities for an extended length oftime for sufficient cooling, or to enable relatively fast line speeds. Apressure head 228 is shown supplying molten resin to the nip.Alternatively an extruder 4, as shown in FIG. 1, can be employed. Hoop220 is preferably of metal.

What is claimed is:
 1. In an apparatus for continuously molding fastenerelements integral with a base web from a flowable resin, the apparatuscomprising a cylindrical mold roll rotatable about an axis of rotationand defining small fastener element-shaped mold cavities in a moldingregion of the surface thereof, and pressure-applying means to applyoperating pressure to force the resin into said cavities at a pressurezone in the vicinity of the molding region, said pressure-applying meansand mold roll defining a mold gap therebetween at the molding region forforming said base web, the apparatus characterized in that the apparatusincludes means to maintain said mold gap at a desired thickness profileacross the width of said wide web under said operating pressure.
 2. Theapparatus of claim 1 in which the molding region of the mold roll islonger than about 12 inches to produce a correspondingly wide web. 3.The apparatus of claim 1 in which the pressure applying means is capableof applying load to said mold roll in the range of about 1000 to 1600pounds per lineal inch along said mold roll.
 4. The apparatus of claim 1in which said mold roll comprises an axially arranged stack of a largemultiplicity of disks, at least many of which have mold cavities attheir peripheral surfaces.
 5. The apparatus of claim 1 in which saidmeans to maintain the mold gap comprises a moving support member on theside of said mold roll generally opposite said pressure-applying means,said support member disposed to engage the peripheral surface of themold roll with sufficient force to resist radial deflection of said moldroll.
 6. The apparatus of claim 5 in which said pressure-applying meanscomprises a pressure roll, said mold gap comprising a nip between saidmold roll and pressure roll.
 7. The apparatus of claim 5 in which saidpressure-applying means comprises a nozzle assembly for introducing saidresin to the pressure zone under pressure, said mold gap comprising agap between said nozzle assembly and the mold roll.
 8. The apparatus ofclaim 5 further comprising means to extract heat from the surface of thesupport member to cool the support member.
 9. The apparatus of claim 3further comprising a support member controller to vary the amount ofengagement between the mold roll and the support member in response tooperating conditions.
 10. The apparatus of claim 9 further comprising asensor to provide operating condition information to the support membercontroller.
 11. The apparatus of claim 10 in which the sensor isconstructed to detect the presence of molded resin on the peripheralsurface of the mold roll, the controller being constructed to disengagethe support member from the peripheral surface of the mold roll whenresin is not present.
 12. The apparatus of claim 10 in which the sensoris constructed to respond to a condition of the apparatus that isrelated to the pressure in the pressure zone.
 13. The apparatus of claim1 in which the depth of the mold cavities from said surface is betweenabout 0.004 and 0.035 inches.
 14. The apparatus of claim 13 in which thedepth of the mold cavities from said surface is between about 0.005 and0.020 inches.
 15. The apparatus of claim 13 in which the depth of themold cavities from said surface is between about 0.006 and 0.012 inches.16. The apparatus of claim 13 in which the mold cavities define theshape of functional fastener elements.
 17. The apparatus of claim 16 inwhich said functional fastener elements are hook elements constructed toengage loops or fibers.
 18. The apparatus of claim 1 in which said moldcavities at least partially define the shape of loop or fiber-engaginghook elements, each element having a pedestal or stem portion and atleast one head portion that projects to a side of said pedestal or stemportion.
 19. The apparatus of claim 5 in which the support member has aperipheral surface that is resiliently deformable to conform, in thevicinity of its engagement with the mold roll, generally to theperipheral surface of the mold roll.
 20. The apparatus of claim 19 inwhich the portion of the support member that directly contacts thesurface of the mold roll is of a resilient substance.
 21. The apparatusof claim 20 in which said portion is of elastomeric material.
 22. Theapparatus of claim 19 in which the support member comprises a generallycylindrical roll arranged to rotate about an axis.
 23. The apparatus ofclaim 19 in which the support member comprises a belt supported toengage the mold roll.
 24. The apparatus of claim 1 in which said meansto maintain the mold gap comprises a means to elastically deform theshape of said pressure-applying means, to conform to radial deflectionof the mold roll.
 25. The apparatus of claim 24 in which saidpressure-applying means comprises a pressure roll, said mold gapcomprises a nip between said mold roll and pressure roll, and said meansto elastically deform is constructed to bend the axis of said pressureroll to maintain the mold gap.
 26. The apparatus of claim 24 in whichsaid pressure-applying means comprises a nozzle assembly for introducingsaid resin to the pressure zone under pressure, said mold gap comprisesa gap between said nozzle assembly and the mold roll, and said means toelastically deform is constructed to bend said nozzle assembly along thelength of said mold gap to maintain the mold gap.
 27. The apparatus ofclaim 1 in which said pressure-applying means comprises a pressure rollrotatable about an axis and positioned to form a nip with said mold rollto provide said mold gap, said means to maintain the mold gap includinga controller to vary the angle between the axes of said pressure andmold rolls to introduce skew to compensate for mold roll deflectionunder said operating pressure.
 28. An apparatus for continuously moldingtwo streams of fastener product from flowable resin, each comprising abase web with integral fastener elements, the apparatus comprising acylindrical mold roll rotatable about an axis and defining smallfastener element-shaped mold cavities in the surface thereof in amolding region, first and second pressure-applying means to applyelevated operating pressure to force the resin into said cavities atcorresponding first and second pressure zones, said first and secondpressure-applying means and mold roll defining corresponding first andsecond mold gaps therebetween for forming said base webs in said moldingregion, and first and second product-removing means to remove theproduct from the mold roll, said first and second pressure-applyingmeans being arranged on generally opposite sides of said mold roll, suchthat bending loads applied to said mold roll by said elevated operatingpressure are substantially balanced.
 29. The apparatus of claim 28wherein the molding region of the mold roll is of about 12 inches ormore in length to produce correspondingly wide webs.
 30. The apparatusof claim 28 in which said first and second pressure-applying means eachcomprises a pressure roll, said first and second mold gaps eachcomprising a nip between said mold roll and a corresponding saidpressure roll.
 31. The apparatus of claim 28 in which said first andsecond pressure-applying means each comprises a nozzle assembly forintroducing said resin to the corresponding pressure zone underpressure, said first and second mold gaps each comprising a gap betweena corresponding said nozzle assembly and the mold roll.
 32. Theapparatus of claim 1 wherein said pressure-applying means is constructedto apply first and second operating pressures at corresponding first andsecond said pressure zones at first and second mold gaps, respectively,with said mold roll.
 33. The apparatus of claim 32 wherein saidpressure-applying means comprises a nozzle assembly for introducingresin to said first pressure zone at said first operating pressure, saidfirst mold gap comprising a gap between said nozzle assembly and themold roll.
 34. The apparatus of claim 33 wherein said pressure-applyingmeans further comprises a pressure roll, said second mold gap comprisinga nip between said mold roll and pressure roll.
 35. An apparatus forcontinuously molding small fastener elements integral with a base webfrom a flowable resin, the apparatus comprising a cylindrical mold rollrotatable about an axis and defining fastener element-shaped moldcavities at a surface thereof in a molding region, and pressure-applyingmeans to apply operating pressure to force the resin into said cavitiesat a pressure zone, said pressure-applying means and mold roll defininga mold gap therebetween for forming said base web, the apparatusincluding a roll arranged to engage said mold roll with substantialforce, and which has a resiliently deformable surface to conform, in thevicinity of its engagement with the mold roll, generally to theperipheral surface of the mold roll in said molding region.
 36. Theapparatus of claim 35 in which said roll having a resiliently deformablesurface comprises a pressure roll positioned to form a wide nip withsaid mold roll to provide said mold gap.
 37. The apparatus of claim 36in which said molding region of the mold roll is of about 12 inches ormore in length to produce a correspondingly wide web.
 38. The apparatusof claim 35 in which said roll having a resiliently deformable surfacecomprises a support roll disposed to engage the mold roll on the sidegenerally opposite said pressure-applying means to resist deflection ofsaid mold roll.
 39. The apparatus of claim 35 for producing a laminatedfastener product comprising a molded web and a backing material, whereinsaid resilient roll and said mold roll define therebetween a laminatingzone for laminating said molded web to said backing material.
 40. Anapparatus for continuously molding fastener elements integral with abase web from a flowable resin, comprising a cylindrical mold rollrotatable about an axis and defining fastener element-shaped moldcavities at a surface thereof, pressure-applying means to apply elevatedoperating pressure to force the resin into said cavities at a pressurezone, said pressure-applying means and mold roll defining a mold gaptherebetween for forming said base web, and a belt arranged to engage asurface of said mold roll.
 41. The apparatus of claim 40 in which saidbelt is arranged to engage the mold roll on the side generally oppositesaid pressure-applying means to resist radial deflection of said moldroll.
 42. The apparatus of claim 40 in which said belt and said moldroll define a laminating zone therebetween for laminating said moldedweb to a backing material.
 43. The apparatus of claim 40 in which saidbelt is constructed to extract heat from the surface of said mold roll.44. In an apparatus for continuously molding fastener elements integralwith a base web, the apparatus comprising a cylindrical mold rollrotatable about an axis and defining fastener element-shaped moldcavities in the peripheral surface thereof in a molding region, a nozzleassembly to introduce a flowable resin to said cavities, said nozzleassembly being constructed and arranged to apply operating pressure toforce the resin into said cavities at a pressure zone, said nozzleassembly and mold roll defining a mold gap therebetween for forming saidbase web, the apparatus characterized in that the apparatus includesmeans to maintain said mold gap at a desired thickness profile acrossthe length of said molding region under said operating pressure.
 45. Theapparatus of claim 44 wherein the molding region of said mold roll is ofabout 12 inches or more in length to produce a correspondingly wide web.46. The apparatus of claim 44 in which said means to maintain the moldgap comprises a support member disposed to engage the mold roll on theside generally opposite said nozzle assembly with sufficient force toresist axial deflection of said mold roll, and a controller constructedto vary the amount of engagement between said support member and saidmold roll.
 47. The apparatus of claim 46 in which said support memberhas a peripheral surface that is resiliently deformable to conform, inthe vicinity of its engagement with the mold roll, generally to theperipheral surface of the mold roll.
 48. The apparatus of claim 44 inwhich said means to maintain the mold gap comprises at least oneactuator to elastically bend said nozzle to conform to radialdeflections of the mold roll to maintain the mold gap, and a controllerconstructed to control said actuator to vary the amount of bending ofthe nozzle assembly.
 49. An apparatus for continuously molding fastenerelements integral with a base web, the apparatus comprising acylindrical mold roll rotatable about an axis and comprising multiplestacked disks having fastener element-shaped mold cavities in theirperipheral surfaces in a molding region, a cylindrical pressure rollarranged to engage said mold roll at a nip and to form a mold gap atsaid nip for forming said base web, the pressure roll constructed toapply operating pressure to force the resin into said cavities, anextrusion die to introduce a flowable resin to said nip, and means tomaintain said mold gap at a desired thickness profile across saidmolding region under said operating pressure.
 50. The apparatus of claim49 wherein said molding region of the mold roll is of about 12 inches ormore in length to produce a correspondingly wide web.
 51. The apparatusof claim 49 in which said means to maintain the mold gap comprises asupport roll arranged to engage the mold roll on the side generallyopposite said pressure roll with sufficient force to resist radialdeflection of said mold roll, and a controller constructed to controlthe amount of engagement between the support roll and the mold roll inresponse to operating conditions.
 52. The apparatus of claim 49 in whichsaid means to maintain the mold gap includes a controller to vary theangle between the axes of said pressure and mold rolls to introduce skewto compensate for mold roll radial deflection under said elevatedoperating pressure.
 53. An apparatus for continuously molding fastenerelements integral with a base web, the apparatus comprising acylindrical mold hoop rotatable about an axis and having fastenerelement-shaped mold cavities in its peripheral surface, at least onedriven roll arranged to engage an inner surface of said mold hoop todrive said hoop, and a pressure-applying means arranged to applyoperating pressure to force the resin into said cavities at a pressurezone, said pressure-applying means and mold roll defining a mold gaptherebetween for forming said base web.
 54. The apparatus of claim 53further comprising means to maintain said mold gap at a desiredthickness profile across the width of said web under said operatingpressure.
 55. The apparatus of claim 53 further comprising means toextract heat from said inner surface of the mold hoop.
 56. A method ofcontinuously molding fastener elements on one broad side of a sheetproduct opposite another broad side having surface features, comprisingproviding an apparatus including a cylindrical mold roll rotatable aboutan axis and defining fastener element-shaped mold cavities at aperipheral surface thereof, a cylindrical pressure roll having aresilient, conformable surface arranged to engage said mold roll at anip and to form a mold gap at said nip for forming said base web, thepressure roll constructed to apply operating pressure to force the resininto said cavities, and an extruder die to introduce molten resin tosaid nip, passing a sheet product having surface features through thenip with the molten resin such that the resilient surface of thepressure roll conforms in the vicinity of the surface features toprotect the surface features of the product as they pass through thenip, thereby forming fastener elements integral with a base web on abroad side of the sheet product.
 57. The method of claim 56 for formingan abrasive sheet product having molded fastener elements on one sideand abrasive particles on the other side, in which the surface featurescomprise abrasive particles.
 58. The method of claim 56 in which thesurface features comprise a decorative texture.
 59. The method of claim56 in which the sheet product comprises a wall covering.